A Revolutionary Guards battle ship approaches a US Navy destroyer, forcing the destroyer to deviate from its course.

An Iranian Islamic Revolutionary Guard battle ship acted “unprofessional but also provocative” while approaching a US Navy’s destroyer Mahan at high speed eventually forcing the Americans to deviate from their course, according to Fox News citing a US officials.

The Americans said the Iranian vessel had its weapons manned and came within approximately 1,000 yards of the US destroyer.

The Mahan attempted bridge-to-bridge communication with the Iranians but got no response. They fired warning flares, blared warning sirens, and even manned the firing positions, and eventually strayed to avoid collision. Despite the provocations, the Mahan did not fire any warning shots, The officials said.

It isn’t the first time. About four months ago, Mahan was involved in a similar incident in the Strait of Hormuz and fired three warning shots at Iranian vessels. They came “within 900 yards or so” of the US destroyer. All radio calls, flares, bells and whistles to signal the Iranian ships to stay away, had no effect.

Pentagon spokesman Capt. Jeff Davis told CNN there had been 35 incidents of unsafe or unprofessional behavior by Iranian vessels in 2016, although the “vast majority” had occurred in the first half.

“Such high-speed approaches and manning of the firing positions, despite warnings from the destroyer, are clearly provocative behavior,” one of the officials said of the Iranians. The Iranian ship did not fire warning shots.